Skating on in-line or tandem roller skates is a fast-growing recreational activity. These skates usually include a synthetic boot and attached frame which rotatably mounts a wheel on each of a plurality of wheel axles that extend between a pair of parallel side rails. The side rails have opposed apertures through which each wheel axle extends. Each wheel axle usually has a bolt-like configuration and is inserted through the apertures of the side rails from one side thereof with the threaded end of the bolt extending beyond the other side rail. A nut is tightened onto the threaded end to attach the wheel securely to the skate.
It has been observed that even well tightened nuts and bolts used to attach the wheels to the frame of an in-line roller skate tend to loosen as a result of road vibration and shock forces imparted to the bolts and nuts during skating use. Such forces cause the tightened nuts and bolts to gradually loosen, and the nut, and in extreme cases the axle, may work free from the frame. Without regular inspections and tightening, such loosening can cause deteriorating skate performance and eventually pose safety problems for the skater.
It has been further observed that it can be somewhat difficult to determine when a nut has been tightened just the right amount to the threaded end of the axle. Failure to tighten the nut enough will result in its working loose more quickly than usual, while overtightening it can result in gouging damage to the frame as the nut is forced to cut into the frame side rail. Proper tightening is not a great problem during initial assembly of the skate by the manufacturer since torque wrenches can then be used to determine optimum tightening. It can, however, present a problem for the skater when rotating or replacing the wheels, or tightening a nut which has become loose, because a torque wrench will usually not be available.
A partial solution to these problems is to use a bolt in combination with a lockwasher/washer to reduce the tendency of the axle to loosen, but loosening does still occur. The lockwasher/washer combination does not remove the need for a torque wrench, and the extra washers and lockwashers do add extra weight and add additional parts to assemble and inventory. In addition, such parts are easily lost during wheel rotation or replacement and they add extra length to the axle and increase the risk of the more elongated axle scratching or gouging objects along the skater's path. Consequently, use of washers and lockwashers has not been a satisfactory solution.
It would be desirable to have a fastening system for assembling a wheel to the frame of an in-line roller skate so that the wheel is not subject to loosening during skating use. It would also be desirable to have a fastening system that would enable the assembler, in particular, the consumer, to determine without a torque wrench when the threaded fastener was properly tightened onto the threaded end of the axle, thus avoiding the correlative problems of overtightening of the wheel axle with its potential frame damage, and undertightening the axle with the risk of premature loosening of the wheel. The present invention provides a solution to these long existing problems.